How do I calculate the last day of the month in SQL? - sql

Question

Specifically MSSQL 2005.

Answer 1

Here's a solution that gives you the last second of the current month. You can extract the date part or modify it to return just the day. I tested this on SQL Server 2005.
select dateadd( s, -1, dateadd( mm, datediff( m, 0, getdate() ) + 1, 0 ) );
To understand how it works we have to look at the dateadd() and datediff() functions.
DATEADD(datepart, number, date)
DATEDIFF(datepart, startdate, enddate)
If you run just the most inner call to datediff(), you get the current month number since timestamp 0.
select datediff(m, 0, getdate() );
1327
The next part adds that number of months plus 1 to the 0 timestamp, giving you the starting point of the next calendar month.
select dateadd( mm, datediff( m, 0, getdate() ) + 1, 0 );
2010-09-01 00:00:00.000
Finally, the outer dateadd() just subtracts one second from the beginning timestamp of next month, giving you the last second of the current month.
select dateadd( s, -1, dateadd( mm, datediff( m, 0, getdate() ) + 1, 0 ) );
2010-08-31 23:59:59.000
This old answer (below) has a bug where it doesn't work on the last day of a month that has more days than the next month. I'm leaving it here as a warning to others.
Add one month to the current date, and then subtract the value returned by the DAY function applied to the current date using the functions DAY and DATEADD.
dateadd(day, -day(getdate()), dateadd(month, 1, getdate()))

Answer 2

SELECT DATEADD(M, DATEDIFF(M, '1990-01-01T00:00:00.000', CURRENT_TIMESTAMP), '1990-01-31T00:00:00.000')
Explanation:
General approach: use temporal functionality.
SELECT '1990-01-01T00:00:00.000', '1990-01-31T00:00:00.000'
These are DATETIME literals, being the first time granule on the first day and last day respectively of the same 31-day month. Which month is chosen is entirely arbitrary.
SELECT DATEDIFF(M, '1990-01-01T00:00:00.000', CURRENT_TIMESTAMP)
This is the difference in whole months between the first day of the reference month and the current timestamp. Let's call this #calc.
SELECT DATEADD(M, #calc, '1990-01-31T00:00:00.000')
This adds #calc month granules to the last day of the reference month, the result of which is the current timestamp 'rounded' to the last day of its month. Q.E. D.

Answer 3

Try this:
DATEADD (DAY, -1, DATEADD (MONTH, DATEDIFF (MONTH, 0, CURRENT_TIMESTAMP) + 1, 0)

Answer 4

They key points are if you can get first day of current month,Last Day of Last Month and Last Day of Current Month.
Below is the Step by Step way to write query:
In SQL Server Date Starts from 1901/01/01( Date 0) and up to now each month can be identified by a number. Month 12 is first month of 1902 means January. Month 1200 is January of 2001. Similarly each day can be assigned by unique number e.g Date 0 is 1901/01/01. Date 31 is 1901/02/01 as January of 1901 starts from 0.
To find out First day of Current Month(Current Date or a given date)
First we need to check how many months have passed since date 0(1901/01/01).
SELECT DATEDIFF(MM,0,GETDATE())
Add same number of month to date 0(1901/01/01)
SELECT DATEADD(MM, DATEDIFF(MM,0,GETDATE()),0)
Then we will get first day of current month(Current Date or a given date)
To get Last Day of Last Month
We need to subtract a second from first day of current month
SELECT DATEADD(SS,-1,DATEADD(MM, DATEDIFF(MM,0,GETDATE()),0))
To get Last Day of Current Month
To get first day of current month first we checked how many months have been passed since date 0(1901/01/01). If we add another month with the total months since date 0 and then add total months with date 0, we will get first day of next month.
SELECT DATEADD(MM, DATEDIFF(MM,0,GETDATE())+1,0)
If we get first day of next month then to get last day of current month, all we need to subtract a second.
SELECT DATEADD(SS,-1,DATEADD(MM, DATEDIFF(MM,0,GETDATE())+1,0))
Hope that would help.

Answer 5

Using SQL2005, you do not have access to a helpful function EOMONTH(), So you must calculate this yourself.
This simple function will works similar to EOMONTH
CREATE FUNCTION dbo.endofmonth(#date DATETIME= NULL)
RETURNS DATETIME
BEGIN
RETURN DATEADD(DD, -1, DATEADD(MM, +1, DATEADD(DD, 1 - DATEPART(DD, ISNULL(#date,GETDATE())), ISNULL(#date,GETDATE()))))
END
Query to perform:
SELECT dbo.endofmonth(DEFAULT) --Current month-end date
SELECT dbo.endofmonth('02/25/2012') --User-defined month-end date

Answer 6

Some links to possible answers:
http://www.extremeexperts.com/sql/Tips/DateTrick.aspx
http://www.devx.com/tips/Tip/14405
http://blog.sqlauthority.com/2007/08/18/sql-server-find-last-day-of-any-month-current-previous-next/
http://www.sqlservercurry.com/2008/03/find-last-day-of-month-in-sql-server.html

Answer 7

DECLARE
#Now datetime,
#Today datetime,
#ThisMonth datetime,
#NextMonth datetime,
#LastDayThisMonth datetime
SET #Now = getdate()
SET #Today = DateAdd(dd, DateDiff(dd, 0, #Now), 0)
SET #ThisMonth = DateAdd(mm, DateDiff(mm, 0, #Now), 0)
SET #NextMonth = DateAdd(mm, 1, #ThisMonth)
SET #LastDayThisMonth = DateAdd(dd, -1, #NextMonth)
Sometimes you really do need the last day of this month, but frequently what you really want is to describe the time interval of this month. This is the best way to describe the time interval of this month:
WHERE #ThisMonth <= someDate and someDate < #NextMonth

Answer 8

For completeness, in Oracle you'd do something like ...
select add_months(trunc(sysdate,'MM'),1) ...
or
select last_day(sysdate)+1 ...

Answer 9

DATEADD(dd, -1, DATEADD(mm, +1, DATEADD(dd, 1 - DATEPART(dd, #myDate), #myDate)))